Phytochemical extraction systems, methods, and devices

ABSTRACT

This disclosure describes systems, methods, and devices for phytochemical extraction. One example extraction system includes two solvent columns, a material column, and a dewaxing column. The solvent columns store and provide solvent for stripping target chemicals from plant material in the material column. The solvent mixed with target chemicals passes into the dewaxing column, where the target chemicals are separated from waxes and lipids. Cooling is applied to elements of the system by way of an open-loop CO2 refrigeration method. Solvent is moved from the solvent columns to the material column by creating a pressure differential between the two solvent columns.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.17/385,872, entitled “PHYTOCHEMICAL EXTRACTION SYSTEMS, METHODS, ANDDEVICES,” filed Jul. 26, 2021; which is a continuation of U.S. patentapplication Ser. No. 16/434,060 (now U.S. Pat. No. 11,071,926), entitled“PHYTOCHEMICAL EXTRACTION SYSTEMS, METHODS, AND DEVICES,” filed Jun. 6,2019; which is a continuation of U.S. patent application Ser. No.15/339,816 (now U.S. Pat. No. 10,315,130), entitled “PHYTOCHEMICALEXTRACTION SYSTEMS, METHODS, AND DEVICES,” filed Oct. 31, 2016; whichclaims the benefit of priority from U.S. Provisional Patent ApplicationNo. 62/360,737, entitled “SOLVENT DEPRESSURIZATION DEVICES, SYSTEM, ANDMETHODS,” filed Jul. 11, 2016; U.S. Provisional Patent Application No.62/373,284, entitled “EXTRACTION COLUMN FOR A PHYTOCHEMICAL EXTRACTIONSYSTEM,” filed Aug. 10, 2016; and U.S. Provisional Patent ApplicationNo. 62/373,275, entitled “CLEAR LID WITH RETAINER CLAMPS FOR ACOLLECTION VESSEL IN A PHYTOCHEMICAL EXTRACTION SYSTEM,” filed Aug. 10,2016, all of which applications are incorporated herein by reference intheir entireties.

TECHNICAL FIELD

The present disclosure relates to phytochemical extraction systems,methods, and devices.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a block diagram of a phytochemical extraction system accordingto one embodiment.

FIG. 2 is a perspective view showing some components of a phytochemicalextraction system according to one embodiment.

FIGS. 3A-3G show elements of a phytochemical extraction system accordingone embodiment.

FIGS. 4A-4C show views of a filter spool according to one embodiment.

FIG. 5 shows a logical block diagram of a pressure assist manifold.

FIGS. 6A and 6B provide views of an example implementation of a pressureassist manifold according to one embodiment.

FIGS. 7A and 7B provide views of an example implementation of a pressureassist manifold according to one embodiment.

FIG. 8 shows a collection vessel.

FIGS. 9A-9D are views of a retainer clamp.

DETAILED DESCRIPTION

FIG. 1 is a block diagram of a phytochemical extraction system 100according to one embodiment. The system 100 includes a material column1, a dewaxing column 2, a first solvent column 3, and a second solventcolumn 4. Each of the columns is a jacketed column such as those shownand described in U.S. Provisional Patent Application No. 62/373,284,entitled “EXTRACTION COLUMN FOR A PHYTOCHEMICAL EXTRACTION SYSTEM,”filed on Aug. 10, 2016.

In overview of the system 100 and its operation, the material column 1is filled with material, such as the plant matter from whichphytochemicals are to be extracted. Each of the solvent columns 3 and 4hold a volume of liquid solvent. By forcing warm water or other heatedliquid into the jacket of column 4, the liquid solvent boils, whichcreates head pressure in column 4. The head pressure is relieved intothe head of column 3 via conduit 4 a, which forces solvent from column 3up through the dip tube 3 b, and into the material column 1. The solventwashes the material in the material column 1, and the extract (insolution with the solvent) is forced into the dewaxing column 2, wherethe target phytochemicals are separated from waxes and lipids that werealso stripped from the material during the solvent wash in the materialcolumn 1.

Elements and aspects of this extraction system and process are describedin additional detail below.

CO2 Open-Loop Refrigeration

This disclosure introduces the concept of liquid carbon dioxideopen-loop refrigeration. CO2 has long been used as a powerfulrefrigerant, known as R-744. While CO2 refrigeration in itself is notnew, the application and adaptation for its use in the describedjacketed columns is novel, and advantageous over previous coolingmethods.

The described technique has several advantageous features. First, CO2 isnon-toxic, so it may be safely vented into the atmosphere. This allowsthe described process to skip the compression side of the standardrefrigeration cycle. This saves us the significant cost of a condensercore and compressor. Instead, the atmosphere is treated as athermodynamic heat reservoir, and releases the expanding CO2 gas asexhaust. We thus refer to this technique as “open-loop refrigeration” asopposed to a traditional closed-circuit system which recycles itsrefrigerant.

Jacketed columns and vessels are usually used with a heat-exchangefluid, such as ethanol, glycol, or aqueous salt solution. Arecirculating chiller is often used to cool and pump this heat-exchangefluid through the jackets to cool the vessels. Such chillers areexpensive refrigeration systems, comprised of both a traditionalevaporator and condenser cores, with a compressor to electrically drivethe refrigerant in a closed-loop. Additionally, such chillers are oftenincapable of removing a significant amount of heat at low temperatures,without requiring a considerable expense for multiple stages ofcompressor and refrigerant. Even when price is not the prohibitingfactor for such an instrument, their energetic requirement of 3-phasepower, and their electrical consumption, can be an impediment to theiruse.

The jacket of a vessel itself can be treated as a refrigerationevaporator core. This “removes the middleman” of cooling a circulatingheat-exchange fluid, significantly reducing the cost and complexity ofthe cooling operation.

The described technique relies on the fact that CO2 is cheap and readilyavailable from industrial gas suppliers worldwide. At $0.30 per pound,it is cheaper to release it as an expendable cooling agent than to payfor the cost of recompressing and condensing it. CO2 is ideal for thedescribed purposes because it has a relatively high Enthalpy ofEvaporation (at 574 kJ/kg, compared to 199 kJ/kg for the much lowerboiling N2). Furthermore, the triple-point of CO2 is at 5.11 atm, farabove Standard Pressure.

By leaving the evaporator-core (column jacket) open at its exhaust port,the liquid CO2 is exposed to 1 atmosphere of pressure, causing part ofits mass to boil rapidly to vapor while the remaining mass is forced tofreeze into dry ice snow, which settles and accumulates inside thejacket. Dry ice has a temperature fixed by its sublimation phase-changeat roughly −109.2° F., or −78.5° C., which it turns out is a verybeneficial set-point for the purposes of cooling and condensinghydrocarbon solvents butane and propane. Furthermore, the Enthalpy ofSublimation of the solid form of dry ice is approximately 58% greaterthan as a boiling liquid. This makes the dry ice residue that fills thejacket very efficient at holding a low temperature near its sublimation“set-point” inside the column it surrounds.

The described process, in typical embodiments, uses a cryogenic dewar ofrefrigerated liquid CO2, 200 L, and 350 psi. Larger dewars are availableas permanently installed “micro-bulk” tanks. CO2 pressure must be keptabout 200 psi to maintain adequate feed pressure. If the internalpressure is too low, caused by the liquid inside being too cold, aPressure-Building Valve can be opened to warm and pressurized the headspace. Cylinders of compressed CO2, with a dip-tube for liquidwithdrawal, can be used instead, but they are not recommended asinternal pressures at room temperature can exceed 750 psi and may bedangerous.

The process involves slowly releasing a steady amount of liquid CO2 intothe cooling jacket of a column, controlled by a regulating needle valve.The liquid is allowed to expand under atmospheric pressure, thusundergoing phase changes both to vapor and to solid form. The CO2 may beinjected either from bottom to top, or top to bottom, the describedjacketed columns have ports near the top and the bottom of the jacket.In the latter configuration, the process will slowly fill the jacketcompletely, at which point the backpressure will cause the flow to stop.Each column is outfitted with a “CO2 controller” comprising a regulatingneedle valve and a pressure relief valve (“PRV”). We have tested PRVsfrom 10-100 psi and we prefer values from 80-100 psi as this is abovethe triple-point and allows the CO2 to remain liquid in an over-pressureevent. A CO2 control assembly with a PRV is shown in FIG. 3G.

The process further includes turning the needle valve from the CO2supply off when either 1) the PRV releases, or 2) the exhaust flow ofCO2 vapor stops, with or without PRV release. Note that CO2 may form dryice in the PRV and prevent it from releasing. Thus, a blockage ofexhaust vapor is sufficient to indicate the jacket is full and supplyshould be turned off to prevent the jacket pressure from equalizing withthe internal supply pressure of the dewar. Column jackets are engineeredto sustain a higher pressure than the vent valve on the supply dewar(350 psi), thus building a safety margin into the system. In someembodiments, a human monitors the operation to determine when to shutthe needle valve. In other embodiments, needle valve regulation isperformed by an automatic pressure-governing system that regulates CO2supply and operation.

Alternatively, a PRV>80 psi may be installed at the top of a column as aback-pressure regulating exhaust valve, and liquid CO2 may be fed intothe bottom port of the column. So long as the vapor pressure in thecolumn exceeds the triple-point pressure of CO2 (approximately 75 psi)it is able to remain a liquid, and it will fill the jacket and slowlyboil away. In this modality, the simmering liquid CO2 has a boilingpoint (i.e., set-point temperature) that is a function of theback-pressure regulator. Use of an adjustable back-pressure regulatorwill allow the user a crude, but very simple mechanism to control thisboiling temperature “set-point”.

Secondary Dewaxing Column

This disclosure also introduces a component referred to as a “secondarydewaxing column”, and a corresponding technique called “secondary stage,single-solvent dewaxing.” The described column and corresponding processfilters and separates by means of differential solubility. FIGS. 1 and 2show a secondary dewaxing column 2 according to one embodiment. FIG. 3Ashows a secondary dewaxing column 2.

Many plants that are processed by the described techniques have inertcompounds, such as waxes and lipids, that are soluble along with thephytochemicals that we are pursuing. A goal is to separate these lipidsout from initial solution by means of differential solubility andprecipitation. It is a property of physics that the amount of solute asolvent can hold is proportional to temperature. Different solutes willhave affinity for a given solvent based on their differing chemistry.When a solute becomes super-saturated in a solution, either by reducingthe solution's temperature, or by condensing the solution throughevaporation, there is a tendency for the solute to precipitate out ofsolution into a solid form. This precipitate will often settle out orremain suspended in the liquid, where it can be either decanted of orfiltered from the remaining solution. The described techniques takeadvantage of the fact that the phytochemical compounds of interestremain soluble at lower temperatures than the waxes we are trying toseparate.

Previous to my invention, dewaxing was accomplished by storing flasks orbeakers of often flammable and volatile solutions in a cold freezer,giving the waxes time to precipitate and separate, before filteringthrough a vacuum-assisted Büchner funnel. This poses problems for thetechnician as the volatile solvent can ignite in the freezer'selectronics, and its volatility increases as it is exposed to the airand warms.

Also previous to my invention, some vertically oriented designs used dryice to cool a secondary vessel, below the material column. This isdisadvantageous, as it limits the size of the material column and thedewaxing vessel beneath it to what is practical under an ordinaryceiling height. Additionally, dry ice has a fixed “set-point” of −109.2°F. which may be too cold for some intended applications.

My observation is that the same type of column used to hold the materialfor the primary extraction can also be used to hold solution in asecondary stage. Placing these columns side-by-side on a horizontal rack(see FIG. 2 ) provides a more flexible form-factor than stacking themvertically. Additionally, the above-described CO2 refrigeration processis used to cool this secondary stage. By throttling refrigerant on andoff, the cooling effect can be modulated, thereby controlling thetemperature of the solution inside the column with greater effect thancooling with dry ice.

The process, described with reference to labeled components shown inFIG. 1 , starts with two columns positioned next to each other: column 1(FIG. 1 ) is called the “material column” (“matCol”) and is filled withthe material we intend to extract from; column 2 is called the “dewaxingcolumn” (dewaxer) and is initially empty. Both columns are fitted with afilter medium at the bottom. The top of the matCol 1 is plumbed to thesolvent supply tank 3, while the bottom is plumbed to the top of thedewaxer 2. Shut-off valves are fitted at the end of both columns tocontrol fluid movement. By this means, solvent may be fed down throughthe top of the material column 1, filling it completely until it isforced out the bottom and back into the top of the dewaxer 2, fillingthe dewaxer completely.

As shown in FIGS. 1 and 3A, the dewaxer is fitted with a large viewingsight-glass at both its top (2 a) and bottom (2 b). FIGS. 3B and 3C alsoshow views of a top sight glass. FIG. 3D shows a view of a bottom sightglass. The sight-glass 2 a at the top allows the operator to see whensolution had filled the material column and begins filling the dewaxer.The sight glass 2 a also allows the operator to more precisely controlthe rate of flow, and insures that the operator can fill the dewaxer 2completely without over-filling. The sight-glass 2 b at the bottomallows the operator to see when the dewaxing precipitation reaction isfinished, and determine when to drain the dewaxer 2. These are bothimportant to our efficient operation, and the sight glasses must be ableto tolerate the extremes of both pressure and temperature.

Once the dewaxer 2 is filled with solution, the valve connecting it tothe material column is closed and the vessel is cooled. This can beaccomplished in two ways:

-   -   1. First, the top of the dewaxer 2 is fitted with a recovery        port 2 c from which solvent vapor may be drawn from the vessel        into another recovery vessel. This may be accomplished by use of        either a pump, or by thermodynamic condensation at the other        end. Releasing vapor from the head space will lower its pressure        and cause the solution inside the vessel to boil, causing it to        cool evaporatively, and also condensing the liquid volume of the        solution.    -   2. After the solution has optionally been condensed and        evaporatively pre-cooled, we turn on the CO2 refrigeration in        the dewaxer jacket, further cooling it to the desired set-point.        In the case of butane solvent, the desired temperature to        precipitate plant waxes is around −40 degrees. This temperature        is higher for solvent mixes containing isobutene and propane.

Once the target temperature is reached, the vessel is held there forapproximately 30-60 minutes. The operator will observe a reaction wherethe solution first turns from clear to cloudy. This is the beginning ofprecipitation. Gradually the precipitates will gather into largerparticles and settle out of solution. It is helpful to pack the dewaxcolumn with some sort 3-dimensional coarse filtration medium, to captureand hold these particles while keeping them suspended about the finer2-dimensional filters at the bottom.

After 30-60 minutes, the operator will observe that the cloudy solutionhas coagulated and separated and becomes qualitatively clear again. Atthis point the solution is drained through the fine filters 2 d (5-40microns; positioned below the lower sight glass 2 b of the dewaxer 2)into a collection pot 2 e where the solvent can be separated from thedesired phytochemical solute by means of distillation and recovery. Toaccomplish this it is necessary to induce a pressure of 50-100 psi inthe headspace of the dewaxer 2, by means of an inert gas such asregulated nitrogen, or by introducing heated vapor of the primarysolvent itself. The material column, still filled with solvent-soakedextracted media, can be heated through its jacket in order to providethe heated solvent vapor pressure. This technique is thus referred to as“pressure-assist” or “warm-vapor pressure-assist”.

Note that the described dewaxing process is in some ways similar to thevacuum-assisted Büchner funnel filtration technique, with the importantdifference that the closed-loop system does not have to be opened up tomove the solution, and the volatile solvent does not have to be exposedto air or the environment, where it could be ignited. Thus, thedescribed dewaxing column is sometimes referred to as a “closed-loopBüchner funnel”.

Note that filtration can be a difficult step in this process. If thefilters are too coarse, waxes will pass through them under pressure, andif they are too fine then they will clog frequently, increasing the timeit takes to drain, and lengthening run-times. Column packing material,or 3-dimensional filtration medium, is on approach to the problem.

To improve filtration, a novel device called a “filter spool” isprovided. FIGS. 4A-4C show a filter spool according to one embodiment. Afilter spool is a small section of tubing, using a standard clampferrule at each end, which has been machined to accept a thin rigid discmade of electrically welded, or sintered, mesh of precise porosity.These discs are clamped between the gaskets and the ferrules of thefilter spool, making a fluid-tight seal. Much care has been taken tostudy the porosity of these filter discs, and the pressure drop betweenthem. Empirical results have shown that no more than two filter discsshould be used in series before the pressure drop across them affectsour ability to push liquid through the column. Consequently, if morefilters are needed, it is recommended that head pressure be renewed in asequence of filtration columns, with no more than two filter discs ineach. For practical purposes, a progressive filter stack of 20 micronand 10 micron provides excellent performance.

In addition to the filtration techniques above, an alternativedecanting-style technique is described. Precipitated waxes tend to beheavier than solution and settle to the bottom, where they form a layeron the filters and thereby restrict flow through them. Theabove-described approach includes the addition of a 3-dimensional columnpacking medium to capture and trap precipitation particles.Alternatively, it is possible to remove the fine 2-dimensional filtersfrom the bottom of the dewaxing vessel, and place them in a small modulebelow the main dewaxer, separated by a shut-off valve. The bottom of thedewaxer is fitted with a small section of tubing that protrudes up intoit, through the cap at its bottom. This short section of tubing willdrain the entire column-volume of liquid above it, but none below, justas a siphon-tube inserted to the same depth would decant it from above.By allowing the precipitates to settle to the bottom of the dewaxer,without filtration below it, rather than capturing in the columnpacking, it accomplishes many of the same goals:

-   -   1. The short tubing drains all of the solution above it, through        the shut-off valve and the filter discs below the dewaxer, while        leaving the sediment at the bottom undisturbed.    -   2. The majority of the precipitate stays in the bottom of the        dewaxer, and does not touch the fine 2-dimensional filters or        contribute to clogging them.    -   3. The sediment can be easily flushed from the dewaxer through a        second shut-off valve directly through the bottom of the cap.        This greatly eases cleaning the dewaxer, and there is no longer        need for the column packing.

Note that these two dewaxing techniques can be used in series to getbetter results through two-stage dewaxing: 1) first removing the bulk ofprecipitation through a decanting-filtration dewaxer; and 2) followed bya second cooling and precipitation in a Büchner-funnel style filtration.

Solvent/Recovery Columns

The described systems and methods include a novel way to supply,pre-cool, and recover solvent by means of storing the solvent in columnsinstead of tanks. Traditionally, a larger tank is used for supply, andit is commonly chilled down to operating temperatures with dry ice.

A long thin column, or a short fat disc, has a much more efficient heatexchange property than a tank, because both have a higher surface areato volume ratio. Heat exchange is accomplished through the skin of thevessel, so higher surface area is advantageous. A sphere has the lowestsurface area to volume possible, and approximates the shape of a stockytank. Of the column and disc shapes, the column is much more practicalfrom a fabrication and usage perspective.

By combining the CO2 jacket refrigeration method described above, and byusing several cooled, jacketed column to hold solvent, it is possible toefficiently and quickly cool solvent down to operating temperatures,without the difficulty of working with dry ice. In practice, oneimplementation has been tested to cool 15 pounds of butane solvent from70 F to −80 F in 10 minutes using CO2 refrigeration. This is far fasterthan using dry ice on an equivalent tank.

One issue that must be overcome is the fact that hydrocarbon solventslike butane and propane have very low vapor pressures at such coldtemperatures. For example: n-butane butane at −80 F has a vapor pressurearound 28 in Hg, nearly a compete vacuum. This makes it difficult tomove the solvent out of a tank or column without the aid of some kind ofpump. To resolve this, a method called “pressure-assist” is used topressurize the headspace of the cold solvent column, and force the coldliquid out a column dip-tube.

With reference to FIG. 1 , two solvent columns 3 and 4 are arrangedside-by-side on a horizontal rack. The first column 3 is cooled with CO2refrigeration, while the second column 4 is heated by warm watercirculated through its jacket. The water needs to be at a temperaturethat exceeds the boiling point of the solvent. In typical applications,hot tap water (e.g., about 50 degrees C.) can be used. The headspace ofthe warm column is connected to the headspace of the cold column by ahose 4 a which is regulated with a needle valve 3 a. The pressurizedwarm vapor inside the heated column 4 will flow into the headspace ofthe cold column 3 when the valve is opened, pushing the cold liquid downand out the bottom, or up a dip-tube 3 b into the top of the materialcolumn 1.

Note that the warm vapor will simultaneously condense inside the coldsolvent column 3, which will cause the liquid inside the warm column 4to boil and continually cool. For this reason the jacket of column 4must continue to circulate warm water to maintain temperature andpressure. Eventually all of the warm solvent will condense inside thecold column and pass through the dip-tube into the material column 1. Ifthe initial amount of solvent that is desired is split roughly equallybetween the warm column 4 and cold column 3, then the entire volume ofboth columns will eventually pass through the material column.

Once the cold solvent column 3 is empty, it can be repurposed as arecovery column, to condense the solvent vapor as it is distilled off ofthe final extract solution in the collection vessel 6. This isaccomplished by connecting the headspace of the collection pot to theheadspace of the cooled solvent column 3, and running the CO2refrigeration process described above. The evaporation of the CO2 in thejacket of the column now drives condensation of the solvent vapor insidethe vessel itself, condensing it back into a liquid and lowering thetemperature and pressure inside the vessel to continually draw moresolvent vapor in. The final result will be that all of the solvent boilsoff from the collection vessel 6, leaving only the pure phytochemicalextract behind, while condensing back into the solvent column 3, anddraining out the bottom into a storage tank 5.

FIGS. 3E and 3F show views of two solvent columns. In FIG. 3E, a storagetank 5 is visible at right. As shown in FIGS. 1 and 3F, the bottom ofthe warm and cold columns can be plumbed with a manifold 5 b whichconnect them both to this tank as a reservoir. As the cold solventcondenses in the column 3, it drains to the tank, thus keeping theentire cold column surface clear for condensation. In this mode, therefrigerated solvent column is acting as a heat-exchanger and condenser,much like a cooled coil does in an alcohol still.

Pressure-Assist Manifold

The phytochemical extraction system 100 includes a “pressure-assistmanifold,” which is a device for switching from a liquid to a vapor feedfrom the outlet of a storage tank, while simultaneously pressurizing thetank's headspace from an external pressure source. This is necessary tomake the fluid in the tank flow out, without the use of a pump, when thefluid in the tank has insufficient vapor pressure itself againstexternal back pressure. This is the case with these common solvents usedin phytochemical extraction: (1) butane, isobutane, and/or propane, atlow temperatures, in any combination; (2) ethanol; or (3) any other highboiling point solvent (pentane, hexane, etc.).

FIG. 5 shows a logical block diagram of a pressure assist manifold 500.The manifold 500 includes a needle valve 501 having two ports, a tee 502having three ports, and a three-way valve 503 having three ports. Thefirst port of the needle valve 501 is connected to a pressure source anda second port is connected to the first port of the tee 502. The secondport of the tee 502 is connected to a vapor port of a tank 510. The tank510 may be, for example, one of the solvent columns or the materialcolumn shown in FIG. 1 . The third port of the tee 502 is connected tothe first port of the three-way valve 503. The second port of thethree-way valve 503 is connected to a liquid port of the tank 510. Thethird port of the three-way valve 503 provides the output of themanifold. The output of the manifold is typically connected to the inputof the next column in the system 100 of FIG. 1 .

The manifold 500 provides the following features. “Throttle” pressuremay be controlled by the single needle value 501 or regulator, for boththe liquid and vapor feed, simultaneously. The needle valve operates inthe (0,1) interval and is connected to N2 pressure source or to warmvapor pressure assist (another tank of butane at higher temperature).

Liquid feed, vapor feed, or OFF is selected by the single 3-way valve503, allowing the user to switch back and forth without disconnectingany hoses. While this is possible with some conventional systems, it isnecessary in those applications for the operator to move connectionsfrom the liquid to vapor ports manually.

Vapor feed is used to force the low-pressure solvent out of the materialcolumn, dewaxing column, or any other stage that comes after themanifold. Regulated nitrogen or warm primary solvent vapor (or any otherpropellant) can be used as an external pressure source.

FIGS. 6A and 6B provide views of an example implementation of a pressureassist manifold according to one embodiment.

FIG. 8 shows a collection vessel 6. The collection vessel 6 is used tocollect extract from an extraction column. As shown in another view inFIG. 7B, the collection vessel 6 is fitted with a clear lid that allowsthe operator to view the contents of the vessel.

In this embodiment, the clear lid is made from ½″ thick polycarbonate.At 6 or more inches of width, the material has a low bending moment andwill begin to dome noticeably at 50 psi, and will pop off around 150psi.

FIGS. 9A-9D show a cross-barred retainer clamp 80, which is a clamphaving one or more integral cross bars 81. The clamp 80 is also visiblein FIGS. 7B and 8 . The cross bars are constructed from ½″×¾″ flat baron 8″ clamps, and ½″×½″ on 6″ clamps.

The cross-barred retainer clamp along with the clear lid forms a workingmechanical system. In particular, the steel cross bar 81 prevents thepolycarbonate cap from doming, keeping the cap flat, which keeps thecircumference from shrinking and slipping out from under the S-linestyle tri-clamp. As the pressure increases inside of the collectionvessel 6 and the cross bars 81 begin to flex, the cross bars 81 drawtheir welded ends closer together, thus tightening the clamp onto thecap and ferrule. The cross bar 81 must be precisely welded to the clampin order for this to work. Some embodiments provide 0.000-0.005″ ofclearance between the bottom of the bars 81 and the top of the clearlid, so that the bars 81 do not scratch the clear surface duringinstallation, and so that there is no slack before the lid engages thebars 81 for support.

While embodiments of the invention have been illustrated and described,as noted above, many changes can be made without departing from thespirit and scope of the invention. Accordingly, the scope of theinvention is not limited by the above disclosure.

The invention claimed is:
 1. A method for CO2 open-loop refrigeration ina phytochemical extraction system including a first column that includesa jacket that surrounds an inner vessel configured to contain solvent,the method comprising: connecting a source of pressurized liquid CO2 toan inlet port of the jacket via a needle valve and a pressure-reliefvalve, wherein the inlet port is located at a top end of the firstcolumn; opening an exhaust port of the jacket, wherein the exhaust portis located at a bottom end of the first column, wherein the top end isabove the bottom end; cooling the surface of the inner vessel byintroducing the liquid CO2 into the jacket, thereby causing a firstportion of the liquid CO2 to boil and a second portion of the liquid CO2to freeze into dry ice snow which accumulates inside the jacket andcools the surface of the inner vessel; and when the pressure-reliefvalve releases, closing the needle valve to stop the introduction of theliquid CO2.
 2. The method of claim 1, wherein the pressure-relief valvehas a cracking pressure in the range 80-100 psi.
 3. The method of claim1, further comprising: when flow of CO2 from the exhaust port stops,closing the needle valve to stop the introduction of the liquid CO2. 4.The method of claim 1, wherein the source of liquid CO2 is a tank ofliquid CO2 having a pressure of about 200 psi.
 5. The method of claim 4,further comprising: when the pressure in the tank is below 200 psi,opening a pressure-building valve to warm and pressurize head space inthe tank.
 6. The method of claim 1, further comprising: connecting asolvent source to an input port of the inner vessel; condensing gaseoussolvent from the solvent source into liquid solvent on the cooledsurface of the inner vessel; and collecting the liquid solvent withinthe inner vessel.
 7. The method of claim 6, wherein connecting thesolvent source includes connecting a collection vessel to the input portof the inner vessel, wherein the collection vessel collects solventafter it has passed through a material column of the phytochemicalextraction system.
 8. The method of claim 6, wherein connecting thesolvent source includes connecting a second column to the input port ofthe inner vessel, wherein the second column includes include a jacketthat surrounds an inner vessel that contains liquid solvent.
 9. Themethod of claim 8, further comprising: circulating water through thejacket of the second column, wherein the water is at least 50 degreesCelsius, thereby warming the inner vessel of the second column andcausing the liquid solvent to boil and pass into the input port of theinner vessel of the first column.
 10. The method of claim 6, furthercomprising: connecting a pressure-assist manifold including: a needlevalve having a first port and a second port, wherein the first port ofthe needle valve is connected to the solvent source; a tee having afirst port, a second port, and a third port, wherein the first port ofthe tee is connected to the second port of the needle valve, wherein thesecond port of the tee is connected to the input port of the innervessel of the first column; a three-way valve having a first port, asecond port, and a third port, wherein the first port of the three-wayvalve is connected to the third port of the tee, wherein the second portof the three-way valve is connected to a liquid port of the inner vesselof the first column, wherein the third port of the three-way valveprovides an output of the pressure-assist manifold.
 11. The method ofclaim 10, further comprising: providing liquid or vapor from the innervessel of the first column to the output of the pressure-assist manifoldwithout disconnecting any hoses, wherein the three-way valve selectsbetween liquid feed, vapor feed, and off.
 12. The method of claim 10,wherein the pressure-assist manifold further comprises a check valvecoupled to third port of the three-way valve.
 13. The method of claim 1,wherein the solvent is one of propane, isobutane, or propane.
 14. Amethod for CO2 open-loop refrigeration in a phytochemical extractionsystem including a first column that includes a jacket that surrounds aninner vessel configured to contain solvent, the method comprising:connecting a source of pressurized liquid CO2 to an inlet port of thejacket via a needle valve, wherein the inlet port is located at a bottomend of the first column; connecting a pressure-relief valve to anexhaust port of the jacket, wherein the pressure-relief valve has acracking pressure of at least 80 psi, wherein the exhaust port islocated at a top end of the first column, wherein the top end is abovethe bottom end; and cooling the surface of the inner vessel byintroducing the liquid CO2 into the jacket, thereby causing a firstportion of the liquid CO2 to boil and a second portion of the liquid CO2to freeze into dry ice snow which accumulates inside the jacket andcools the surface of the inner vessel.
 15. The method of claim 14,wherein the source of liquid CO2 is a tank of liquid CO2 having apressure of about 200 psi.